While the amount of PM building up in a particulate filter (DPF) is increasing (until reaching a DPF regeneration start determination value Thpms), one or both of an EGR amount reduction control in which an EGR amount to be recirculated into an air intake system is reduced so that the amount of NOx in exhaust gas increases, and a NOx release control in which a NOx storage catalyst is caused to release NOx, are executed to increase the amount of NO 2 supplied to the particulate filter, whereby the PM buildup rate of the particulate filter is reduced, and therefore, the regeneration interval of the DPF is increased.